Malignant disease after radiation treatment of benign gynaecological disorders. A study of a cohort of metropathia patients.

One hundred and seven cases of malignant tumours occurred among 788 women irradiated 1912 to 1977 for metropathia. One hundred and seventy-three women out of 1,219 referred for the same diagnosis and not irradiated developed a malignant tumour. The tumours were diagnosed between 1958 and 1982. The relative risk of malignant tumours among the irradiated women was 1.22 and among the non-irradiated 1.09 compared to cancer registry data. A statistically non-significant increase of the relative risk was found in the irradiated patients for tumours of the rectum (1.58), colon (1.46), and the nervous system (1.67). A decreased overall relative risk was seen for cancer of the breast (0.92) after irradiation, but women treated at the age of 50 or more had an increased risk (2.08). The relative cancer risk of the heavily irradiated sites was not increased during the first 20 years after irradiation, but a statistically significant increase of the risk was seen after 30 years.